1. Field of the Invention
This invention relates in general to subsea wells, and in particular to hydraulic connectors for connecting hydraulic lines in a subsea well to a surface vessel or other subsea equipment.
2. Description of the Prior Art
Offshore drilling and well production systems generally have hydraulic or electro-hydraulic control systems for operating the subsea functions. Subsea completions, for example, almost invariably have hydraulically operated tree connectors and valves. Hydraulic connectors are used to connect a subsea tree to its wellhead, a riser to a blowout preventer stack, and hydraulic control lines to the tree valves.
Two predominant types of hydraulic connectors are used. In one type, individual pin and box connectors are used. In the other or multiway type, a mandrel or upper connector member inserts into a receptacle or lower connector member. The mandrel has a hydraulic seat with a plurality of passages terminating in ports at the hydraulic seat. These ports align with ports in the receptacle to transmit hydraulic fluid.
The typical multiway connector includes a conical hydraulic seat. The conical male mandrel fits into a corresponding conical female receptacle. The male mandrel has a number of hydraulic ports, each of which is surrounded by an elastomeric seal, which is secured by a threaded retainer. The elastomeric seal is reinforced with an internal metal ring. The female receptacle has internal hydraulic ports which correspond in position to the ports on the mandrel when the mandrel is engaged. A keyway or pin is used to insure proper orientation of the mandrel in relation to the receptacle.
While successful, the conical hydraulic seat surfaces require a complex curvature on the face of the seal element. While this is not a significant problem for elastomers, it would be very difficult to use for metal-to-metal seals. While elastomer seals have many advantages, they have a limited life, do not withstand high temperatures, and are more readily attacked by certain fluids than a metal seal.